1. Field of the Invention
This invention relates to a polymer composition and more particularly to a composition containing a thermosettable cyanate resin precursor and a thermoplast effective to make said resin tougher when cured. It relates to also such a composition containing reinforcing fibres and to cured resin structures made of such a composition.
2. Description of Prior Art
Thermoset resins have been used for many years to make strong non-metallic structures, but have had somewhat limited fields of application because they are brittle. U.S. Ser. No. 253,596, filed Oct. 5, 1988, now abandoned, describes a polymer composition providing a useful improvement in fracture toughness and briefly reviews earlier attempts to meet this requirement. Whereas that U.S. Ser. No. mentions in a general way that the thermoset component of its compositions may be a cyanate resin, we have now identified particular compositions affording a significant advance in performance.